Accurate biopsy procedures require the use of accurate position determination of the site relative to the surface of the subject. Previous procedures have included the use of multiple x-rays or fluoroscopic scans, and careful determination to locate the site on the surface of a patient through which a biopsy probe could be inserted. Since significant time may elapse between the location of the site and the actual biopsy procedure, the accuracy of the process can be compromised due to patient motion and errors in the administration of the procedure.